I have a pallet I'm working on that wants to deal with emojis (allowing emojis to be submitted, stored, etc). i found Rust crate unic_emoji_char which I think would help greatly, but can't get it to work in a pallet. I'm assuming it has something to do with std.

To the cargo.toml I add: unic-emoji-char = { version = "0.9.0", default-features = false }

And in std: "unic-emoji-char/std",

Snips of errors when I cargo test:

error: failed to select a version for `unic-emoji-char`.
the package `pallet-rmrk-core` depends on `unic-emoji-char`, with features: `std` but `unic-emoji-char` does not have these features.

Guessing I just can't use this library, but are there any suggestions for how to do emoji-checking with Rust/Substrate?

1 Answer 1


The std feature is not something that works out of box. It is just a convention that crate authors may or may not stick to.

As you can see, there is no std feature in Cargo.toml of unic-emoji-char here.

Apart from that, compiling code to a runtime implies using the no_std environment (see here for more details) and the crate in question does not seem to declare that in its lib.rs.

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